1. Field of the Invention
The instant disclosure relates to an image sensor; in particular, to an image sensor that can support both the rolling shutter mechanism and the global shutter mechanism, and relates to an image capture device using the same.
2. Description of Related Art
With the development of the photoelectric products, the requirements in regard to the image sensor are stricter. The image sensors can be generally classified into two types. One is the complementary metal-oxide-semiconductor (CMOS) image sensor, and the other one is the charge-coupled device (CCD) image sensor. The CMOS sensor is characterized by low power consumption and less manufacturing cost, and thus has been widely used in photoelectric products.
The image sensor comprises a plurality of pixels arranged in a matrix and a plurality of comparators. In the case that the image sensor has the configuration of the column analog-to-digital converter, the pixels in the same column are connected to the same comparator. Each pixel detects the brightness information and correspondingly generates image data. Each pixel commonly comprises a light-sensing element and a reading circuit composed of at least one output transistor. Specifically, the light-sensing element detects the incident light, and correspondingly outputs and stores charges into the floating diffusion region. The output transistor converts the charges stored in the floating diffusion region to image data and outputs the image data to the comparator. The comparator outputs a corresponding comparison result image data to the image processing circuit according to the image data and a reference voltage to generate corresponding images.
The current image sensors can support two kinds of shutter mechanisms, which are the rolling shutter mechanism and the global shutter mechanism. When the image sensor is working under the rolling shutter mechanism, the pixels are row by row exposed, and image data are generated and row by row provided to the comparator. On the other hand, when the image sensor is working under the global shutter mechanism, all pixels are simultaneously exposed, and row by row provide image data to the comparator.
Each comparator has different voltages when it is working under the rolling shutter mechanism and under the global shutter mechanism. Generally, the current image sensors use two kinds of comparators and the corresponding image processing circuits to respectively process the image data under the rolling shutter mechanism and under the global shutter mechanism. If the same comparator and the corresponding image processing circuit are used to process the image data under the rolling shutter mechanism and under the global shutter mechanism, the various voltage requirements of the comparator will result in difficulty and complexity for designing the comparator. However, using two kinds of comparators and the corresponding image processing circuits to respectively process the image data under the rolling shutter mechanism and under the global shutter mechanism has greater cost and requires a larger element area.